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Full text of "Evaluation of dusts and sprays for the protection of shelled corn from insect attack"

STATE PLANT BOARD 

April 1954 



E-875 



United States Department of Agriculture 
Agricultural Research Service 
Entomology Research Branch 



EVALUATION OF DUSTS AND SPRAYS FOR THE PROTECTION 
OF SHELLED CORN FROM INSECT ATTACK-^ 

By Albert C. Apt 
Stored-Product Insects Section 
Biological Sciences Branch, Agricultural Marketing Service 



In recent years the demand for adequate supplies of insect-free 
grain for milling purposes has caused the emphasis to be placed on 
prevention rather than control of insect pests. Protective dusts and 
sprays provide promising means of protection. Dusts containing 
pyrethrins synergized with piperonyl butoxide are on the market. 

In the fall of 1952 an experiment was undertaken at Beattie, Kans., 
to determine whether these dusts and sprays would protect shelled corn 
from insect attack for long storage periods in farm-type bins. This was 
a cooperative study by the Commodity Research Division of the Grain 
Branch of the Production and Marketing Administration (now the Grains 
and Feeds Section, Market Organization and Costs Branch, Agricultural 
Marketing Service), acting for the Commodity Credit Corporation, and 
the Division of Stored-Product Insect Investigations of the Bureau of 
Entomology and Plane Quarantine (now the Stored-Product Insects 
Section, Biological Sciences Branch, Agricultural Marketing Service). 

Materials 

The corn used in this work was grown in 1949, and had been shelled 
and stored at Beattie since the fall of 1950. The bins were of frame 
construction, 24 by 16 feet and 10 feet high at the eaves, with a capacity 
of 3,000 bushels. 

The corn was infested with several species of grain beetles, the 
saw-toothed grain beetle ( Oryzaephilus surinamensis (L.)) being pre- 
dominant. No weevil infestation was found. 

Nine formulations containing pyrethrins, ryania, or lindane were 
applied to the shelled corn as indicated in table 1. 



ly Part of a dissertation presented in partial fulfillment of the re- 
quirements for the degree of doctor of philosophy in entomology at Kansas 
State College. 



- 2 - 



Table 1. --Spray and dust formulations applied to bins of shelled corn. 



Formulation 



Application 

rate per 
1,000 bushels 



Bins 
treated 



Insecticide 



Percent 

Sprays 

1. Pyrethrins-piperonyl butoxide 

concentrate (5-50) 5 ) 

Carbon tetrachloride 93 7 

Inert ingredients 2 j 

2. Pyrethrins-piperonyl butoxide 

concentrate ( 1 - 10) 1.18 \ 

Water and emulsifier 98.9 f 

Dusts 

3. Pyrethrins 0.05 | 

Piperonyl butoxide .80 V 

Talc 99.15 J 

4. Pyrethrins 0.08 

Sulfoxide 1. 10 

Ground rice hulls 98.82 

5. Pyrethrins 0.08 "\ 

Piperonyl butoxide ' 1.10 V 

Corn-cob flour 98.82 j 

6. Kyania (ground stems) 100 J 

7. Kyania (ground stems) 95.8 \ 

Sulfoxide — 3.2 f 

Inert material 1 .0 J 

8. Kyania (ground stems) 95.8 | 

n- Propyl isome 3.2 > 

Inert material 1.0 J 

9. Lindane L.O I 

Wheat flour 99.0 ) 



Gallons 



Pounds 



100 



100 



75 
100 

45 
60 

45 

60 



45 
60 

45 

60 



Number P. p. m 



1 
I 

2 
2 

2 
1 



1.04 



1.23 



0.89 



1.43 



1.07 
1.43 



804 
1071 

770 
1026 



770 
1026 



8.1 

10.7 



- 3 - 



Procedure 

Twenty-five binfuls of shelled corn were transferred into empty bins, 
and dusts or sprays were applied to the corn during the process. Augers 
were used to transfer the corn. One auger removed the corn from a bin 
and dropped it into the hopper of a second auger, which elevated it into 
an empty bin (fig. 1). The rate of movement was approximately 500 
bushels an hour; thus about 6 hours were required to turn each bin. 

The sprays were applied in a fan-shaped pattern onto the grain 
stream as it dropped from the first auger into the hopper of the second 
auger (fig. 2). Formulation No. 1 was applied by means of a pneumatically 
operated applicator tank equipped with a flowmeter which was set to 
deliver 2 gallons per 1,000 bushels. Formulation No. 2 was applied by 
use of a gear pump set to deliver 8 gallons per 1,000 bushels. 

The dusts were applied to the grain stream, as it was elevated into 
the second bin, by means of an applicator, which was attached to the 
auger near its lower end (fig. 3). The applicator had internal rotating 
agitator blades to prevent the dust from bridging and to insure an even 
flow into the auger. The screw conveyor in the auger tube mixed the 
dust with the shelled corn while elevating the corn to the bin, and 
further mixing occurred as the corn fell into the bin. To prevent undue 
loss of dust, the upper end of the auger and the filling hatch of the bin 
were covered with a tarpaulin. After the bins were filled with the dust- 
treated corn, a capping of dust, about 10 pounds per bin, was applied 
by running dust alone through the auger. The corn was then leveled 
and raked to distribute the dust uniformly throughout the top 6 inches. 
Three bins were left untreated as checks. 

The treated bins were sampled at monthly intervals until December 
1953, except for some that were inadvertently fumigated in September. 
Samples were drawn with a 5-foot grain trier from six locations in each 
bin--the top and bottom 5 feet, at the center and about 3 feet from each 
end wall. The samples were sifted and the living insects were counted. 
The mean number of insects per 1,000 grams of shelled corn was then 
computed. 

The three bins treated with formulation No. 2, which contained water, 
were also sampled before treatment and 1 week and 3 weeks after treat- 
ment, and the moisture content was determined with a Steinlite moisture 
meter. 

The samples taken after 2, 4, 7, 9, and 11 months were tested in the 
laboratory to ascertain whether or not enough deposit was present to 
cause insect mortality. Each of the first four samples was infested 
with 25 adult confused flour beetles (Tribolium confusum Duv.), and the 
11 -month sample was infested with 25 adult rice weevils ( Sitophilus 
oryza (L.)). Mortality counts were made after 1 and 3 weeks of exposure. 



The two bins treated with formulation No. 9, containing lindane, were 
sampled and analyzed chemically after 3 months. One bin treated with 
each formulation c ontaining ryania (Nos. 6, 7, and 8) was sampled and 
the residue determined by bioassay. The bioassays were made by 
courtesy of S. B. Penick & Company. 

Samples of shelled corn from each treated bin were forwarded to the 
Chicago Board of Grain Supervisors for an opinion as to the effect of 
treatments on the grade. 

Results 

The numbers of insects found in the treated bins at the various 
sampling periods are given in table 2. In all bins the populations 
showed a pattern usually followed in stored grain in Kansas — that is, 
a decline from October- to December as the temperature drops and a 
low level until the temperature of the grain mass begins to rise in the 
late spring or early summer, this buildup becoming evident in July and 
reaching a peak in September or October. Should the concentration of 
insects be sufficient to cause heating, the population may increase 
instead of decreasing during the winter months. 

The synergized pyrethrins dust in a talc base (No. 3) gave complete 
protection during the entire period from September 1952 to October 1953, 
except for an infestation, which was believed to be due to a roof leak and 
a consequent high-moisture area, in the last month in one bin. The 
increased performance over synergized pyrethrins in an organic base 
(No. 5) is considered to be due to the use of talc, which is known to give 
some protection against stored-grain insects. However, this formula- 
tion caused the corn to be graded DI,Q (distinctly low quality) and there- 
fore would not appear to be acceptable for use on shelled corn that will 
enter market channels. 

The bin treated with ryania-n-propyl isome(No.8) at 60 pounds per 
1,000 bushels and one of two treated at 45 pounds also gave complete 
protection for the entire period. 

The bins treated with ryania alone (No. 6) and ryania-sulfoxide (No. 7) 
at both rates and one bin treated with lindane (No. 9) at 60 pounds had the 
next lowest insect populations and gave almost complete protection. 

The bins treated with synergized pyrethrins in organic diluents 
(Nos. 4 and 5) at 100 pounds per 1,000 bushels held the insect population 
down to a relatively low level. 

Of the two sprays, synergized pyrethrins in a water base (No. 2) 
gave the better protection, being about equal to that given by dusts Nos. 4 
and 5. The spray containing carbon tetrachloride (No. 1) gave only 
partial control in the critical August-September period. 

The moisture content of the corn treated with synergized pyrethrins 
in a water base (No. 2) decreased rather than increased after the treat- 
ment as shown in table 3. 



- 5 - 



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The r esults of th'- laboratory tests, wherein adults of the confused 

The con elation between these tests and the population levels found :n 
the treated bins is very good. It will be noted that treatments giving 

Digitized by the Internet Archive 

i n ?fi1 ^ 

merit of insects- - No. 1, No. 5 at 75 pounds, and No. 9 at 45 pounds-- 
gave very poor kill of the rice weevil after 11 months. The formula- 
tions of synergized pyrethrins dust (Nos.3, 4, and 5 at 100 pounds), 

lower mortality. 

■ 

. 

given in table 4. The lindane residues at the end of 3 months were only 



The corn from only two series of bins was rated as not a< ceptable 

graded as DLQ (distinctly low quality); and corn treated with ryania- 

■ 



http ://arch i ve . org/detai Is/attprod ustOO u n it 



- t - 



Table 4. --Mortality of test insects confined in corn treated with various dusts 
and sprays. 25 insects in each test. 



Formulation 


Rate of appli- 
cation per 
1,000 bushels 


Months 
after 
treatment 


Percent mortality after 
indicated period 


Confused flour 
beetle 


Rice weevil 


1 week 


3 weeks 


1 week 


3 weeks 




Gallons 












1. Pyrethrins-piperonyl 


2 


2 


3 


40 


- 


- 


butoxide- carbon 




4 


- 


42 


- 


- 


tetrachloride 




7 


1 


42 


- 


- 






9 


1 1 


1 9 


- 


- 






1 1 


- 


- 


1 1 


1 1 * 


2. Pyrethrins-piperonyl 


8.3 


2 


2 


2 


- 


- 


butoxide- water 




4 




9fi 










7 


1 


82 


- 


- 






9 


2 


9 


- 


- 






1 1 


- 


- 


46 


46* 




7.5 


2 


16 




- 


- 






4 




A 
4 










7 


3 


7 


- 


- 






9 


21 


31 


- 


- 






] 1 


- 


- 





0* 




Pounds 












3. Pyrethrins-piperonyl 


100 


2 


36 


65 






butoxide-talc 




4 




23 










7 





57 










9 


6 


26 










1 1 






40 


40 


4„ Pyrethrins-sulfoxide- 


100 


2 




38 






ground rice hulls 




4 




51 










7 


3 


1 H 










9 


1 5 


L6 










1 1 






38 


42 



Table 4. - -Continued 









Percent mortality after 




Rate of appli- 


Months 




indicated period 


Formulation 


cation per 


after 


(_ on i us 


ed flour 








1,000 bushels 


treatment 


De< 


Rice weevil 








1 week 


3 weeks 


1 week 


3 weeks 


Pounds 












5. Py rethrins -piperonyl 


100 


2 




52 


- 


- 


butoxide-corn cob 




4 




41 






flour 




7 


• 

1 


32 








9 


18 


36 








11 


- 


- 


1 9 


AO 


75 


2 




- 


- 


- 




4 




35 








7 


D 


31 








!' 


2 


15 








11 


- 


- 


a 

□ 


A* 

o 


6. Ryania 


60 


2 




62 


- 


- 




4 




96 








7 


1 1 


99 








9 


6 


80 








1 1 


- 


- 


70 


96 


45 


2 




50 


- 


- 




4 




85 








7 


D 


1 00 








!' 


21 


76 








1 1 


- 


- 


58 


92 

J mm 


7. Kyania -sulfoxide 


60 


2 




44 








4 




77 








7 


o i 
82 


100 








9 


19 


84 








1 1 






68 


96 


45 


2 




46 








4 




96 








7 


11 


75 








9 


21 


86 








1 1 






70 


70 



I 



Table 4. - Continued 



Formulation 


Rate of appli- 
cation per 
1,000 bushels 


Months 
after 
treatment 


Percent mortality after 
indicated period 


Confused flour 
beetle 


Rice weevil 


1 week 


3 weeks 


1 week 


3 weeks 




TU/~\ i inn c 












8. Ryania-n-propyl 


60 


2 


- 


64 


- 


- 


isome 




4 




9 9 










7 


JO 


1 UU 










9 




1 C\C\ 

1 UU 










11 






1 UU 


1 UU 




45 


2 


- 


62 


- 


- 






< 

4 




9 7 










7 


DO 


r 1 
o 1 










9 


o 



n o 
9o 










11 






n a 
94 


n a 
9 4 


9. Lindane -flour 


60 


2 


- 


100 


- 


- 






4 




99 










7 


"\ f\r\ 
1 UU 


1 UU 










9 




inn 
1 UU 










11 






9b 


9o 




a r* 

45 


2 




44 










4 




99 










7 


5 


2 










9 


61 


98 










1 1 












Check 




2 


0.7 












4 




11.0 










7 


0.7 


17.0 










9 


6.0 


6.0 










11 






5 


8* 



^Samples showing evidence of reproduction after being held for 6 weeks at 
80° F. and 70 percent relative humidity. 



- 10 - 



Summary 

Various spray and dust formulations containing synergized pyrethrins, 
ryania, or lindane were applied to twenty-five 3,000-bushel bins of shelled 
corn at Beattie, Kans., in the fall of 1952, as the corn was transferred 
from one bin to another. Monthly samples from six points in each bin 
were taken through December 1953, and the insect populations were 
determined for each. No insects were found after treatment with a 
pyrethrins-piperonyl butoxide-talc dust at 100 pounds, or with ryania- 
n-propyl isome dust at 60 pounds per 1,000 bushels. The first formula- 
tion caused downgrading of the corn because of the inorganic base. 

The insect population was held to a very low level by ryania, ryania- 
sulfoxide, and ryania -n-propyl isome dusts at 45 pounds or lindane- flour 
dusts at 60 pounds per 1,000 bushels. The ryania-sulfoxide formulation 
caused downgrading of the corn because of an objectionable odor. 

Dusts of pyrethrins-sulfoxide-ground rice hulls and pyrethrins- 
piperonyl butoxide-corn cob flour at 100 pounds per 1,000 bushels and a 
spray containing pyrethrins-piperonyl butoxide-water applied at 10 gal- 
lons held insect populations to a relatively low level. A spray containing 
pyrethrins-piperonyl butoxide-carbon tetrachloride and dusts containing 
lindane-flour applied at 45 pounds and pyrethrins-piperonyl butoxide- 
corn cob flour at 75 pounds per 1,000 bushels failed to inhibit the develop- 
ment of dangerous insect populations. 

Tests in which insects were confined for 3 weeks on samples of grain 
taken 2, 4, 7, 9, and 11 months after treatment gave results that correlated 
closely with the populations in the bins. 

The moisture content of corn treated with the water-base spray 
decreased rather than increased in the 3 weeks following application. 

Kyania residues remained high after 7 months but were rather 
variable. Lindane residues after 3 months were only one-thirtieth to 
one-fortieth of the amounts applied. 



- 11 - 




Figure 2„--Spray nozzle attached to 
grain delivery spout for applying 
sprays. 



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